1. Field of the Invention
This invention relates to a magnetic head device used in a photomagnetic recording/reproducing apparatus employing a photomagnetic recording medium, such as a magneto-optical disc.
2. Description of the Related Art
There has been used a photomagnetic recording/reproducing apparatus employing, as a recording medium, a magneto-optical disc having a photomagnetic recording layer comprised of a perpendicular magnetic recording film on a light-transmitting transparent substrate.
The photomagnetic recording/reproducing apparatus has, in a facing relation to a major surface of the magneto-optical disc, run in rotation by a disc rotating driving mechanism, an optical pickup device adapted for radiating a light beam on the photomagnetic recording layer, while having, in a facing relation to the opposite major surface of the magneto-optical disc, a magnetic head device for applying an external magnetic field across the photomagnetic recording layer.
With the magneto-optical disc recording/reproducing apparatus, a magnetic field modulated in magnetic field orientation depending on the information signals to be recorded is applied by the magnetic head device, at the same time as a light beam radiated by the optical pickup device is condensed and illuminated on the photomagnetic recording layer. The portion of the recording layer heated to higher than the Curie temperature by the irradiated light beam and which has lost its coercivity is magnetized depending on the direction of the magnetic field applied by the magnetic head device and subsequently is cooled to lower than the Curie temperature as a result of relative movement of the light beam by rotation of the magneto-optical disc to fix the direction of magnetization to record information signals.
Thus, the conventional magnetic head device includes an electro-magnetic control mechanism adapted for displacing the magnetic head so as to follow up with surface deviations of the magneto-optical disc, in order to maintain a constant spacing between the magnetic head and the magneto-optical disc in a contact-free manner, even although such surface deviations are produced on rotating the magneto-optical disc due to warping or fluctuations in thickness of the magneto-optical disc.
The magnetic head device provided with an electromagnetic control mechanism adapted for maintaining a constant spacing between the magnetic head and the magneto-optical disc is in need of power for driving the electromagnetic control mechanism, thus increasing power consumption. In addition, the magnetic head device is in need of a detection mechanism for detecting the spacing between the magnetic head and the magneto-optical disc thus complicating the mechanism for controlling the magnetic head device. Moreover, the recording/reproducing apparatus is complicated in structure to render it extremely difficult to reduce the size and the thickness of the device itself.
There is proposed a photomagnetic recording/reproducing apparatus having a magnetic head device for recording information signals, with the magnetic head in contact with the magneto-optical disc, in place of the magnetic head device adapted for controlling the magnetic head at a pre-set separation from the magneto-optical disc liable to surface deviations as a result of rotation.
In the magnetic head device employed in this type of the magneto-optical disc recording/reproducing apparatus, a magnetic head device comprised of a magnetic core and a bobbin carrying a coil is supported at the distal end of a head supporting member. This head supporting member is molded as-one with a pair of electrically conductive members comprised of a substantially parallel arrangement of a head supporting portion carrying a magnetic head device, a stationary portion for mounting the magnetic head device in the optical disc recording/reproducing apparatus and a head support arranged between the head mounting portion and the stationary portion.
With the head supporting member, an electrically conductive member is exposed to outside between the stationary portion and the head support to constitute a first resilient flexible portion, while an electrically conductive material is exposed to outside between the head support and the head mounting portion to constitute a second resilient flexible portion.
In the magnetic head device, a slide contact member is mounted on a surface of the magnetic head device facing the magneto-optical disc. This slide contact member slides on the rotated magneto-optical disc to maintain a pre-set separation between the magnetic head device and the magneto-optical disc.
If, with the magnetic head device, the rotated magneto-optical disc is subjected to surface deviations, the first and second resilient flexible portions are resiliently displaced to pivot the head mounting portion and the head support to maintain the posture of the magnetic head device and the slide contact member mounted thereon.
The magnetic head device also carries a flexible wiring board operating as wiring for supplying the current to the coil of the magnetic head device.
In this flexible wiring board, the wiring formed of an electrically conductive material designed as a printed circuit is sandwiched between a pair of flexible insulating films. The flexible wiring board has its one end connected to an external circuit, while having its other end connected to a terminal electrically connected to the coil formed on the head support member for electrically connecting the coil to the external circuit for supplying the current to the coil.
This magnetic head device has the coil terminal connected to the external circuit via the flexible wiring board to make possible current supply to the coil and movement of the hard disc simultaneously along the radius of the disc in synchronism with the optical pickup device.
Meanwhile, with this sort of the magnetic head device, it is necessary, when the magneto-optical disc is run in rotation with the slide contact member in sliding contact with the magneto-optical disc, to perform control so that, even in cases wherein the magneto-optical disc undergoes surface deviations, the slide contact member will maintain a pre-set slide contact posture at all times with the magneto-optical disc. That is, if, when the magneto-optical disc is subjected to the surface deviations, the posture of the slide contact member is in disorder, the separation between the magnetic head device and the magneto-optical disc is transiently broadened to disable correct application of the external magnetic field to cause recording failure.
Also, if the posture of the slide contact member is in disorder, there is a risk of the end of the slide contact member damaging the rotated magneto-optical disc.
In particular, in a portable photomagnetic recording/reproducing apparatus, there are occasions wherein the magneto-optical disc undergoes severe surface deviations due to vibrations applied thereto during use. Thus, it is desired of the magnetic head device that, even if the magnetic head device has changed its height position significantly to follow up with the surface deviations of the magneto-optical disc, the slide contact member can maintain a pre-set posture in order to have slide contact with the magneto-optical disc to enable correct application of the external magnetic field.
In addition, with this magnetic head device, there are occasions wherein, when the magnetic head device is moved radially of the disc in synchronism with the optical pickup device, the flexible wiring plate is slidingly contacted with the head support member or other components of the magneto-optical disc recording/reproducing apparatus to cause destruction of the flexible wiring board. Furthermore, when the magnetic head device is moved axially of the disc in synchronism with the optical pickup device, the flexible wiring board is flexed severely to become entangled with the head support member or driving gears in the device to obstruct smooth movement of the head device.
Thus, with the present magnetic head device, the flexible wiring plate is secured, such as with an adhesive, to the head support member to limit its width of flexure to prevent the flexible wiring board from being slidingly contacted or entwined with the head support member or other components.
However, the operation of securing the flexible wiring board to the head support member with an adhesive is cumbersome to lead to the lowering of productivity of the magnetic head device. Moreover, new components, such as adhesives, are required to increase the number of components. There is also the risk of the flexible wiring board being detached from the head support member due to the lowering of the adhesive power of the adhesive.
Further, with the magneto-optical disc recording/reproducing apparatus employing the above-described magnetic head device, the head mounting portion and the head support member need to be uplifted in a direction away from the major surface of the magneto-optical disc being loaded for providing a spacing for mounting/dismounting the magneto-optical disc.
Thus, with this magneto-optical disc recording/reproducing apparatus, a movement member is abutted against the lower surface of the head support member of the magnetic head device, so that, when mounting or dismounting the magneto-optical disc, this movement member is uplifted for pivoting the head mounting portion and the head support member in a direction away from the major surface of the magneto-optical disc being loaded for providing a spacing for attachment/detachment of the magneto-optical disc.
Further, this head device includes a pivoting amount regulating arm configured for being protruded from a stationary portion towards the head support member and the head mounting portion. This pivoting amount regulating arm includes a regulating piece adapted for compressing against the head mounting portion on pivoting of the head mounting portion and the head support member.
With this magnetic head device, when the head mounting portion and the head support member are pivoted in a direction away from the major surface of the loaded magneto-optical disc, the head mounting portion compresses against the regulating piece of the pivoting amount regulating arm to regulate superfluous pivoting of the head mounting portion and the head support member as well as to set the height position of the as-pivoted head mounting portion.
However, with this magnetic head device, the head mounting portion is abutted against the regulating piece of the pivoting amount regulating arm to regulate its pivoting, instead of the pivoting amount operating member abutted against the lower surface of the head support member uplifting the head support member for pivoting the head mounting portion and the head support member. Thus, if, with the head mounting portion compressing against the regulating piece of the pivoting amount regulating arm, an uplifting pressure is applied further, superfluous load tends to be concentrated in the second resilient flexible portion to cause its deformation.
With the magnetic head device, if the second resilient flexible portion is deformed, the slide contact posture of the magnetic head and the slide contact member with respect to the magneto-optical disc is in disorder to disable correct application of the external magnetic field.